Evaluation of static thermodynamic properties of the ternary molten salt system Li,Na,Be/F, based on the modified Peng-Robinson equation

The static thermodynamic properties of the molten salt system like LiF-NaF-BeF2 influence the design and construction of the fuel salt and coolant in the Molten Salt Reactor for the new generation. In this paper, the equation of state of the ternary system 15%LiF-58%NaF-27%BeF2, over the temperature range of 873.15K to 1073.15K at one atmosphere pressure, is described using Peng-Robinson equation modified by us. And the density of the ternary system is evaluated by this equation directly, and compared with the experimental data. Base on the equation of state, the other static thermodynamic properties such as the enthalpy, entropy and heat capacity at constant pressure are estimated by the residual function method and the fugacity coefficient method respectively. The density calculated by Peng-Robinson equation is in highly agreement with the experimental data, and the enthalpy, entropy and heat capacity evaluated by such two different methods are consistent with each other. We could conclude that the Peng-Robinson equation modified by us could be applicable to evaluate the density of the molten salt system, and we recommend the Peng-Robinson equation to be as the fundament to estimate the enthalpy, entropy and heat capacity of the molten salt system. (author)